(kō'mə) PluralcomasA state of deep unconsciousness, usually resulting from brain trauma or metabolic disease, in which an individual is incapable of sensing or responding to external stimuli.

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(kō'mə) Pluralcomae (kō'mē)

Astronomy The brightly shining cloud of gas that encircles the nucleus and makes up the major portion of the head of a comet near the Sun. As a comet moves along its orbit away from the Sun, the gas and dust of the coma dissipate, leaving only the nucleus. A coma can have a diameter of up to 100,000 km (62,000 mi.). See more at comet.

Physics A diffuse, comet-shaped image of a point source of light or radiation caused by aberration in a lens or mirror. The image appears progressively elongated with distance from the center of the field of view.